'\" te
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.TH EFI_ALLOC_AND_INIT 3EXT "May 16, 2020"
.SH NAME
efi_alloc_and_init, efi_alloc_and_read, efi_free, efi_write, efi_use_whole_disk,
efi_reserved_sectors \- manipulate a disk's EFI Partition Table
.SH SYNOPSIS
.nf
cc [ \fIflag \&.\|.\|.\fR ] \fIfile\fR\&.\|.\|. \fB-lefi\fR [ \fIlibrary \&.\|.\|.\fR ]
#include <sys/vtoc.h>
#include <sys/efi_partition.h>

\fBint\fR \fBefi_alloc_and_init\fR(\fBint\fR \fIfd\fR, \fBuint32_t\fR \fInparts\fR, \fBdk_gpt_t **\fR\fIvtoc\fR);
.fi

.LP
.nf
\fBint\fR \fBefi_alloc_and_read\fR(\fBint\fR \fIfd\fR, \fBdk_gpt_t **\fR\fIvtoc\fR);
.fi

.LP
.nf
\fBvoid\fR \fBefi_free\fR(\fBdk_gpt_t *\fR\fIvtoc\fR);
.fi

.LP
.nf
\fBint\fR \fBefi_write\fR(\fBint\fR \fIfd\fR, \fBdk_gpt_t *\fR\fIvtoc\fR);
.fi

.LP
.nf
\fBint\fR \fBefi_use_whole_disk\fR(\fBint\fR \fIfd\fR);
.fi

.LP
.nf
\fBuint_t\fR \fBefi_reserved_sectors\fR(\fBdk_gpt_t *\fR\fIvtoc\fR);
.fi

.SH DESCRIPTION
The \fBefi_alloc_and_init()\fR function initializes the \fBdk_gpt_t\fR
structure specified by \fIvtoc\fR in preparation for a call to
\fBefi_write()\fR. It calculates and initializes the \fBefi_version\fR,
\fBefi_lbasize\fR, \fBefi_nparts\fR, \fBefi_first_u_lba\fR, \fBefi_last_lba\fR,
and \fBefi_last_u_lba\fR members of this structure. The caller can then set the
\fBefi_nparts\fR member.
.sp
.LP
The \fBefi_alloc_and_read()\fR function allocates memory and returns the
partition table.
.sp
.LP
The \fBefi_free()\fR function frees the memory allocated by
\fBefi_alloc_and_init()\fR and \fBefi_alloc_and_read()\fR.
.sp
.LP
The \fBefi_write()\fR function writes the EFI partition table and creates a
Protective Master Boot Record (PMBR); see below.
.sp
.LP
The \fBefi_use_whole_disk()\fR function takes any space that is not contained
in the disk label and adds it to the last physically non-zero area before the
reserved slice (from slice 0 to slice 6 or unallocated space).
.sp
.LP
The \fBefi_reserved_sectors()\fR function calculates number of sectors
needed to create the reserved partition. The reserved partition is used
by the operating system for internal purposes. The sector size used is
based on the device and is recorded in the \fBefi_lbasize\fR member of
the \fBdkgpt_t\fR structure indicated by the \fIvtoc\fR argument.
A full description of the \fBdk_gpt_t\fR structure appears later in the manual.
.sp
.LP
The \fIfd\fR argument refers to any slice on a raw disk, opened with
\fBO_NDELAY\fR. See \fBopen\fR(2).
.sp
.LP
The \fInparts\fR argument specifies the number of desired partitions.
.sp
.LP
The \fIvtoc\fR argument is a \fBdk_gpt_t\fR structure that describes an EFI
partition table and contains at least the following members:
.sp
.in +2
.nf
uint_t          efi_version;     /* set to EFI_VERSION_CURRENT */
uint_t          efi_nparts;      /* no. of partitions in efi_parts */
uint_t          efi_lbasize;     /* size of block in bytes */
diskaddr_t      efi_last_lba;    /* last block on the disk */
diskaddr_t      efi_first_u_lba; /* first block after labels */
diskaddr_t      efi_last_u_lba;  /* last block before backup labels */
struct dk_part  efi_parts[];     /* array of partitions */
.fi
.in -2

.SS "Protective Master Boot Record"
When a disk receives an EFI label, a protective MBR (\fBPMBR\fR) is also
written containing a single partition of type \fBEEh\fR and spanning the
entire disk (up to the limit of what can be represented in an MBR). By
default that partition is placed in slot 0 of the PMBR and not marked as
active. Some BIOS implementations contain bugs that require the entry to be
placed into a different slot or to be made active in order for the system
to boot successfully. The default behaviour is modified for systems with known
firmware bugs, refer to \fB/usr/share/hwdata/efi.fixes\fR for more
information.

.SH RETURN VALUES
Upon successful completion, \fBefi_alloc_and_init()\fR returns 0. Otherwise it
returns \fBVT_EIO\fR if an I/O operation to the disk fails.
.sp
.LP
Upon successful completion, \fBefi_alloc_and_read()\fR returns a positive
integer indicating the slice index associated with the open file descriptor.
Otherwise, it returns a negative integer to indicate one of the following:
.sp
.ne 2
.na
\fB\fBVT_EIO\fR\fR
.ad
.RS 13n
An I/O error occurred.
.RE

.sp
.ne 2
.na
\fB\fBVT_ERROR\fR\fR
.ad
.RS 13n
An unknown error occurred.
.RE

.sp
.ne 2
.na
\fB\fBVT_EINVAL\fR\fR
.ad
.RS 13n
An EFI label was not found.
.RE

.sp
.LP
The \fBefi_reserved_sectors()\fR function always returns the number of
reserved sectors required. It will always succeed.

.sp
.LP
Upon successful completion, \fBefi_write()\fR returns 0. Otherwise, it returns
a negative integer to indicate one of the following:
.sp
.ne 2
.na
\fB\fBVT_EIO\fR\fR
.ad
.RS 13n
An I/O error occurred.
.RE

.sp
.ne 2
.na
\fB\fBVT_ERROR\fR\fR
.ad
.RS 13n
An unknown error occurred.
.RE

.sp
.ne 2
.na
\fB\fBVT_EINVAL\fR\fR
.ad
.RS 13n
The label contains incorrect data.
.RE

.sp
.LP
Upon successfully completion, \fBefi_use_whole_disk()\fR returns 0. Otherwise,
it returns a negative integer to indicate one of the following:
.sp
.ne 2
.na
\fB\fBVT_EIO\fR\fR
.ad
.RS 13n
An I/O error occurred.
.RE

.sp
.ne 2
.na
\fB\fBVT_ERROR\fR\fR
.ad
.RS 13n
An unknown error occurred.
.RE

.sp
.ne 2
.na
\fB\fBVT_EINVAL\fR\fR
.ad
.RS 13n
The label contains incorrect data.
.RE

.sp
.ne 2
.na
\fB\fBVT_ENOSPC\fR\fR
.ad
.RS 13n
Space out of label was not found.
.RE

.SH USAGE
The EFI label is used on disks with more than 1^32-1 blocks. For compatibility
reasons, the \fBread_vtoc\fR(3EXT) and \fBwrite_vtoc()\fR functions should be
used on smaller disks. The application should attempt the \fBread_vtoc()\fR or
\fBwrite_vtoc()\fR call, check for an error of \fBVT_ENOTSUP\fR, then call the
analogous EFI function.
.SH ATTRIBUTES
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
MT-Level	Unsafe
.TE

.SH SEE ALSO
.BR ioctl (2),
.BR open (2),
.BR read_vtoc (3EXT),
.BR libefi (3LIB),
.BR dkio (4I),
.BR attributes (7),
.BR fmthard (8),
.BR format (8),
.BR prtvtoc (8)
